perfect vs round off

perfect is a noun but round off is not a noun.

Word	Noun	Adjective	Verb	Adverb
perfect	Yes	Yes	Yes	No
round off	No	No	Yes	No

As verbs, round off is a hyponym of perfect; that is, round off is a word with a more specific, narrower meaning than perfect:

Other hyponyms of perfect include optimise, optimize, brush up, polish, polish up, round.

perfect (noun)	round off (noun)
a tense of verbs used in describing action that has been completed (sometimes regarded as perfective aspect)

perfect (adjective)	round off (adjective)
being complete of its kind and without defect or blemish
precisely accurate or exact
without qualification; used informally as (often pejorative) intensifiers

perfect (verb)	round off (verb)
make perfect or complete	express as a round number
	make round
	bring to a highly developed, finished, or refined state